Let’s say You have a HRTF for some direction V. I’ve skipped a lot of details because i want to focus on the most interesting use of HRTFs from the game audio point of view, which is… Using HRTF to create virtual surround sound There are many detailed papers on the subject of HRTF – the topic was studied extensively and many measurements were done. Generally, the higher the frequency, the higher the attenuation. For every direction, the phase and frequency response “of our filter” is different.įor the sound source not on the axis of symmetry the biggest difference is in attenuation – You can see on the plots above that for the sound source to the one side, the ear on the opposite side of the head receives much less acoustic energy (that is intuitive). HRTF is a rather complicated function of frequency and direction. That information is crucial to our brain and one of the main mechanism of determining the direction of the incoming sound: it is, most importantly, used to determine the location of sound source lying on the cone of confusion (where the Interaural Time Difference and Interaural Level Difference are the same). HRTF is an information on how your head, including the pinna acts on different frequencies of the incoming sound. If our head (mainly, but other parts of the body too) acts as a filter, then HRTF is nothing more than that filter’s transfer function. This leads us to… Head Related Transfer Function (HRTF) If you would examine a head as a filter then every person’s would have his own, unique filter characteristic that ultimately shapes the final sound that the brain analyses. The size and shape of the head, dimensions of the pinna and other parts like torso are naturally different for each person, causing slightly different effects for different wave lenghts – therefore recording made inside one person’s ears may sound unnatural for the other. There is one catch though : Everybody is different. Moreover, it includes all the effects like scattering and diffraction of the sound wave on the head, pinna and other parts of the body that are inseparable from the sounds that we hear everyday and are very hard, if not impossible to reproduce.Ī dummy head used to create a binaural recording of the sound of sea on the beach. As a consequence, such a recording already contains all the positional cues that our brain uses to localize the source of sound and other techniques try to reproduce. The effect is similar to what You can hear in the video above – You feel like you’re really there.And that is because of the obvious fact that microphones placed in your ears record sound waves almost the same as those that would normally hit your inner ear. As for binaural recordings, there isn’t really much more to it. How do You do that? Well, you simply put the microphones in the…ears.That’s it. The idea is to record.what our ears really hear. Actually, the only downside is that it works only on headphones. Yet, there are hardly any games that make use of that and if they are, they are not AAA titles…which is strange because (as You could hear) the effect is incomparable with the stereo we’re used to and the method itself (as You’ll read later on) is very easy to implement. The technique itself is more than two times older. Sounds amazing, right? Well, the recording is almost 20 years old. Have You ever heard about the Virtual Barber Shop? If not, then listen to this (use headphones!):
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